Sale 1:

Sold for 25 keys

No outpost

Seller: http://backpack.tf/profiles/76561198090956917#!/compare/1486684800/1486771200

Buyer: http://backpack.tf/profiles/76561198134340160#!/compare/1486684800/1486771200

X = 25

Sale 2:

Sold for 24 keys

No outpost

Seller: http://backpack.tf/profiles/76561198119563409#!/compare/1490313600/1490486400

Buyer: http://backpack.tf/profiles/76561198361512142#!/compare/1490313600/1491091200

X = 24

Sale 3:

Sold for Disco Beat Down Backbiter's Billycock + Spec. KS Australium Knife

http://www.tf2outpost.com/trade/28745527 - B/O of 24

Seller: http://backpack.tf/profiles/76561198238854082#!/compare/1485734400/1485820800

Buyer: http://backpack.tf/profiles/76561198132922680#!/compare/1485734400/1485820800

Easily caps.

X = 24 (Capped by B/O)

Sale 4:

Sold for Disco Beat Down Letches LED (18.5)

No outpost

Seller: http://backpack.tf/profiles/76561198132922680#!/compare/1485820800/1485907200

Buyer: http://backpack.tf/profiles/76561198036254026#!/compare/1485820800/1485907200

X = 19

Sale 5:

Sold for Max's (18)

No outpost

Seller: http://backpack.tf/profiles/76561198132073057#!/compare/1489536000/1489622400

Buyer: http://backpack.tf/profiles/76561198119563409#!/compare/1489536000/1489622400

X = 18

Sale 6:

Quicksold to a buyer for 17 keys

Seller: http://backpack.tf/profiles/76561198119534537#!/compare/1485216000/1485302400

Buyer: http://backpack.tf/profiles/76561198044335614#!/compare/1485129600/1485216000

X = 17

Sellers:

26 keys:

http://i.imgur.com/c6l9AYr.png - 8 days

http://backpack.tf/u/76561198361512142

Sales at:

17

18

19

24 (2x)

25

17 sold to a buyer. Excluding 17.

Sales at 18 and 19 look pretty low. It's also likely that both sellers of those sales were the ones that offered. The hat has also proven to be able to sell for 25 pure. Excluding 18 and 19.

Going with 24-25.